Temporary pancreatic duct stents reduce the rate of pancreatitis due to endoscopic retrograde cholangiopancreatography in patients at high risk for the disorder, Dr. Atsushi Sofuni and colleagues reported in the October issue of Clinical Gastroenterology and Hepatology.
Although post-ERCP pancreatitis usually is mild and resolves with conservative treatment, some patients can develop substantial complications, "and on occasion they are fatal," said Dr. Sofuni of Tokyo Medical University, and associates (Clin. Gastroenterol. Hepatol. 2011 [doi:10.1016/j.cgh.2011.06.033]).
Post-ERCP pancreatitis is thought to arise primarily from impaired drainage from the pancreatic duct, which is thought to result from papillary edema and/or sphincter spasm brought on by the physical manipulation during the ERCP procedure.
The investigators performed a randomized clinical trial to assess whether placement of a temporary pancreatic duct stent during the ERCP would prevent pancreatitis from developing. The stent was designed to keep the duct open for a brief interval after the procedure to allow adequate drainage, and then to dislodge spontaneously within 3 days.
The trial involved 426 consecutive patients undergoing ERCP and related procedures at 37 endoscopic specialty centers in Japan. Half the patients were assigned to receive pancreatic stents and half were not.
The 3-cm-long polyethylene stent was unflanged on the pancreatic duct side but had two flanges on the duodenal side. Abdominal x-rays were performed every morning after the ERCP to track dislodgement. Stents that did not dislodge by the third day were to be removed by duodenoscopy on the fourth day.
After randomization, 12 cases that were found not to meet inclusion criteria and 7 cases with incomplete data were included in the intention-to-treat analysis but were not available for the as-treated analysis, which now comprised 203 patients in the stent group and 204 in the no-stent group.
The distinction between these two analyses became important because the results were different. In the as-treated analysis, the rate of post-ERCP pancreatitis was significantly lower (P = .02) with the stent (7.9%) than without the stent (15.2%), the investigators said.
In contrast, in the intention-to-treat analysis, the rate of post-ERCP pancreatitis was lower, but not significantly so, with the stent (9.4%) than without the stent (14.6%). The overall rate of post-ERCP pancreatitis in this study was approximately 11%, which "agrees in general with previous reports."
There was no significant difference in the rise in serum amylase levels between the stent and no-stent groups.
Stent placement failed in 25 patients (12%) in whom it was attempted. In three of these cases, anatomic deformities of the pancreatic duct were the cause. In another 15 cases, the duct could not be cannulated, and in the remaining 7 cases, the guidewire could not be passed deeply enough.
Six factors were found to put patients at risk for developing post-ERCP pancreatitis: undergoing pancreatography first, not achieving placement of the pancreatic stent, a procedure time of 30 minutes or longer, sampling of the pancreatic tissue by any method, undergoing intraductal ultrasonography, and difficulty in achieving cannulation (defined as taking 15 minutes or longer to do so).
"This indicates that post-ERCP pancreatitis might be affected by other factors as well as papillary edema, such as the direct burden placed on the pancreatic duct" by instrumentation used in tissue sampling and intraductal ultrasonography rubbing against it, the researchers noted.
In cases in which it was difficult to cannulate the bile duct, endoscopists sometimes placed a pancreatic guidewire to facilitate biliary cannulation. Such guidewires were used in approximately 35% of patients who developed post-ERCP pancreatitis, compared with only 8% of patients who did not develop post-ERCP pancreatitis.
"This suggests the possibility of direct damage to the pancreatic duct by the guidewire," they said. Use of a softer, more delicate guidewire might be beneficial when guidewire use cannot be avoided, they added.
This study had no financial support, and the authors stated that they had no conflicts of interest.